The present invention relates to polishing compositions, particularly compositions for polishing plastic products or non-electrolysis nickel plating layers.
A polishing composition for plastic products such as a plastic lens known in the art is a slurry formulated by suspending a polishing agent of aluminium oxide in water and adding a polishing accelerator of aluminium nitride, as disclosed in JP-B-53-3518.
This slurry can polish plastic products at high efficiency and high quality. However, this is a slurry of strong acid and has pH value of about 4-2. On account of the strong acid, a polishing machine or a tool using this polish may rust and the hands of an operator may be roughened. Accordingly, the slurry is apt to harm machines or operators.
In recent years, a memory hard disc for computers or word processors has been made in process where a layer of non-electrolysis nickel plating, also called chemical plating, or a layer of alumite is formed on a substrate of aluminium so that a pre-treatment is performed, the pre-treatment surface is polished, and a layer of storage magnetic medium is formed on the smoothed pre-treatment surface. A general-purpose polishing slurry formulated by suspending a polishing agent of aluminium oxide in water is used as a composition for polishing the pre-treatment surface.
However, the general-purpose polishing slurry is low in efficiency for polishing a layer of non-electrolysis nickel plating or the like and therefore is not practicable. Consequently, a polishing composition for a layer of non-electrolysis nickel plating or the like has been desired.